Family caregivers of patients with advanced cancer are at risk for bereavement- related morbidity. Better communication in the context of cancer care may improve health outcomes of the bereaved. Aims: In a study nested within a parent RCT (R01CA140419) focused on patient outcomes, we propose to examine whether a health communication intervention can lead to better caregiver mental health (Aim 1) and physical health (Aim 2). In Aim 3, we seek to contextualize these findings by conducting mediational analyses and qualitative analyses. The former will explore whether intervention effects are mediated by patient-reported quality of life and patient health care utilization. Qualitative methods will be used to link bereavement outcomes with parent study communication outcomes. Design: Multiple waves of caregiver assessments will be added to a NIH-funded two-site cluster RCT. In that study, oncologists are randomized to usual-care (n=15) or the communication intervention (n=15), which involves two in-office sessions providing individually tailored feedback on their patient communication skills. Patients with advanced cancer and their caregivers seen by oncologists in the usual-care arm (n=128 dyads) will receive usual cancer care. Dyads seen by oncologists in the intervention arm (n=128 dyads) will receive pre-visit coaching and question- prompt lists to enhance their communication skills. In this application, we propose to assess caregiver experiences and outcomes while the patients are alive, as well as 2 and 7 months after the patients' deaths. The 2-month post-mortem assessment will include an audiotaped interview to explore caregivers' experiences with key elements of decision-making: information exchange (e.g., tailored), deliberation (e.g. participation), and socioemotional issues (e.g. respect, abandonment). Main outcomes: Prolonged grief symptoms (PG-13) and physical function (SF-36) 7 months following the patients' deaths. Secondary outcomes include symptoms of depression and anxiety, decisional regret, thoughts of suicide, and disability. For the qualitative analyses, criterion based purposeful sampling will be used to make deliberate comparisons linking the parent study and this one based on 3 criteria: intervention arm, communication quality, and prolonged grief. Significance: This efficient addition to an ongoing RCT is the first attempt to examine the effects on bereavement outcomes of an intervention that could be integrated into routine cancer care. As the intervention is systemic, yet simple and readily disseminated, findings will have implications for cancer care, public health, and policy.